PUBLIC HEALTH ASSESSMENT
HANFORD 1100-Area (USDOE)
RICHLAND, BENTON COUNTY, WASHINGTON
The tables in this section list the contaminants of concern. ATSDR's evaluations of thesecontaminants and determinations of whether exposure to them has public health significanceappear in the subsequent sections of this public health assessment. The Agency selects and discusses these contaminants based upon the following factors:
- concentrations of contaminants on and off the site;
- field data quality, laboratory data quality, and sample design;
- comparison of on-site and off-site concentrations with health assessment comparison values for (1) noncarcinogenic and (2) carcinogenic endpoints; and
- community health concerns.
In the data tables that follow under the On-site Contamination subsection and the Off-siteContamination subsection, listing of a contaminant does not mean that it will cause adversehealth effects from exposures. Instead, the list indicates which contaminants will be evaluatedfurther in the public health assessment.
The data tables include the following abbreviations and acronyms:
| || = Cancer Risk Evaluation Guide |
|= Environmental Media Evaluation Guide |
|= Maximum Contaminant Level |
|= Proposed Maximum Contaminant Level |
|= parts per billion |
|= parts per million |
|= Reference Concentration |
|= Reference Dose |
|= Reference Dose (or Concentration) Media Evaluation Guide|
Comparison values for public health assessment are contaminant concentrations in specific media that are used to select contaminants for further evaluation. These values include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), and other relevant guidelines. CREGs are estimated contaminant concentrations based on one excess cancer in a million persons exposed over a lifetime. CREGs are calculated from EPA's cancer slope factors. EPA's Maximum Contaminant Levels (MCLs) represent contaminant concentrations that EPA deems protective of public health (considering the availability and economics of water treatment technology) over a lifetime (70 years) at an exposure rate of 2 liters of water per day. Proposed Maximum Contaminant Levels (PMCLs) are MCLs that are being proposed. MCLs are regulatory concentrations. EPA's Reference Dose (RfD) and Reference Concentration (RfC) are estimates of the daily exposure to a contaminant that is unlikely to cause adverse health effects. Reference Dose (or Concentration) Media Evaluation Guides (RMEGs) are based on EPA's RfDs and RfCs.
For the purpose of this document, "on-site" will refer to the three equipment maintenanceoperable units -- EM-1, EM-2, and EM-3. The isolated unit, Operable Unit IU-1, is off site.
The EM-1 Operable Unit of the 1100-Area has been the subject of extensive study duringremedial investigation. Phase I of the Remedial Investigation for Operable Unit EM-1 wascompleted in August 1990 (3). Phase II was completed in December 1992 (4). The remainingthree operable units (EM-2, EM-3, and IU-1) were addressed as a limited field investigation(LFI) and focused feasibility study (FFS) in an addendum to the Phase II Remedial Investigationand Feasibility Study of the EM-1 Operable Unit, completed in April 1993 (8). The LFI/FFSapproach differs from the usual CERCLA process. Rather than taking place as an initial detailedevaluation of media contamination, sampling and establishment of media-specific goals takeplace during the remediation process (8).
EM-1 is the only 1100-Area operable unit for which both soil and groundwater data areavailable. Because of the area's past use, DOE representatives believe that soil in EM-2 could becontaminated with trichloroethane, chlordane, and polychlorinated biphenyls (PCBs). Soil inEM-3 could be contaminated with nitrates, lead, carbon tetrachloride, and PCBs. Soil in 1100-IU-1 could be contaminated by fuel spillage and leakage of hydraulic fluid and solvents at theNike sites (8). Quantitative soil data for these operable units were not given in the remedialinvestigation/feasibility study, in the LFI/FFS, or in a record of decision signed in September1993 (3,4,8,9). Groundwater data are available from monitoring wells in EM-2 (located entirelywithin EM-1) and EM-3 (once called the 3,000-Area, between EM-1 and the North RichlandWellfield), but not for 1100-IU-1 (15 miles west of EM-1) (8).
The EM-1 Operable Unit is shown in Figure 2. Contamination known to originate in OperableUnit EM-1 is limited to six suboperable units, a rainwater pool, and one groundwater plume (seeFigure 3). The reported contaminants in EM-1 are motor and hydraulic oils, battery acid,ethylene glycol (antifreeze), solvents and degreasers, paints and paint thinner, and asbestos.
A DOE document suggests the groundwater plume originated at Siemens (Advanced NuclearFuels) just outside the border of the operable unit (compare Figure 2 to Figure 3) (3). Trichloroethene (TCE) and nitrate are the primary contaminants (3,4). This plume is movingnortheast under the Horn Rapids Landfill and toward the Columbia River (Figure 3). SiemensPower Corporation, through its contractor, Geraghty and Miller, Inc., began a remedialinvestigation/feasibility study under the Washington State Model Toxics Control Act (4). Sampling and analysis that supplied data for this public health assessment were conducted by orunder the direction of DOE's contractor, Westinghouse Hanford Company (3).
Soil was sampled either 0-6 inches deep or at the subsurface (more than 6 inches deep) (3). Sampling was not random throughout the operable units but was restricted to areas that DOEinvestigators believed were likely to be contaminated by waste disposal or vehicle maintenanceactivity. Sampling took place from July through October 1989 (18).
Samples were analyzed for contaminants on the EPA target analyte and target compound listsand were tested for ethylene glycol in suboperable units 1100-3 and 1100-4 (3,19). The sampleethylene glycol content was indistinguishable from blanks -- less than 2,000 ppm. ATSDR'scomparison values (EMEGs) for soil contaminated with ethylene glycol are 1,000,000 ppm foradults, 100,000 ppm for most children, and 4,000 ppm for children exhibiting pica behavior(ingestion of non-nutritive substances). None of the samples showed ethylene glycol in amountssufficient to justify further evaluation in this public health assessment (19).
The suboperable units 1100-1 and 1100-4 were not surface-sampled because they had beenbackfilled with sand and gravel; 1100-1 after it ceased to be a designated battery acid disposalsite in 1977 and 1100-4 after tank removal in 1986 (3,4). The location of 1100-4 has since beencovered with concrete. It is under the floor of Building 1171, an indoor vehicle maintenancefacility (compare Figure 2 to Figure 3).
Table 2 below lists substances reported in the Phase I Remedial Investigation (3) atconcentrations exceeding ATSDR's comparison values. These substances will be evaluatedfurther in the assessment to determine whether they could be of public health concern.
Arsenic is not a product or byproduct of any human activities know to have occurred in the 1100-Area; it is an expected constituent of soil of basaltic origin. Variability of basaltic content in soilmay account for variability in soil arsenic content. Arsenic is listed in the table, althoughATSDR does not assume it to be a contaminant generated by DOE, and its concentration issimilar to that expected in regional soil. It was found in the soil at concentrations high enough tojustify further evaluation in this assessment.
Tetramethyloxirane (TMO) was tentatively identified 10-22 feet below the surface. TMO could be migrating towards the groundwater from the paint and solvent pit. TMO may be hazardous by analogy to oxirane (ethylene oxide).
|Substance|| Operable |
|Concentration Rangea (ppm)|| Cancerb Class and |
|Source||Rangec in Washington soil (ppm) |
|Subsurface||Subsurface Depth (ft.)|
|Arsenic||Background||0.15-1.6||0.64-2.7||0.5-21|| Adult 200 |
| RMEG |
| 0.4-8.6 |
|1100-1 battery acid pit||Not reported||0.94-3.2|
|1100-2 paint & solvent pit||1.4-2.3||0.65-1.9||0.5-40|
|1100-3 antifreeze & degreaser pit||1.1-3.4||0.69-1.5||1-10|
|Rainwater pool||1.8-2.6||Not reported||Not applicable|
|1100-6 discolored soil||1.7-2.7||Not reported||Not applicable|
|Horn Rapids Landfill||0.62-3.6||0.37e-4.2e||0-27|
CrIII: Picad Child 2,000;
|Horn Rapids Landfill||0.51-17.1||4.0e-1250||0-27|
| No slope factor |
| EPA |
| NDh-30 |
|1100-1||Not reported||266 |
|Rainwater pool||35f-54.2f||Not reported||Not applicable|
|1100-6||5.0-22.1||Not reported||Not applicable|
|Horn Rapids Landfill||0.38e,g-482e||0.12e,g-854e,i||0-27|
|Trichloroethylene (TCE)||1100-1||Not reported||0.0075e-0.016e||2-4||60 |
|1100-2||0.006||Not reported||Not applicable|
|Horn Rapids Landfill||0.005e||0.005g||0-25|
|Aldrin-R||1100-2||0.001e-3.7e||Not reported||0.0-0.5||0.04 (B2)||CREG (EPA)|
|1100-6||4500e-25000e||Not reported||Not applicable||50 |
|Total PCBsj||1100-1||Not reported||0.299e||1.5-2|| 0.09 |
| CREG |
|1100-3||0.15e||Not reported||Not applicable|
|Rainwater pool||0.3e-42i||Not reported||Not applicable|
|Horn Rapids Landfill||0.1g-3.2e||95 |
based on retention time)
|1100-3||Not reported||220e-280e||10-22 (4 samples in borehole DP8)||RAC (for oxirane or ethylene oxide) |
a Data from reference 3 unless otherwise stated.
b EPA cancer classes: A, human carcinogen; B2, probable human carcinogen with inadequate human studies; C, possible human carcinogen. NTP cancer classes: KC, known carcinogen; RAC, reasonably assumed a carcinogen. IARC: 2A, reasonably assumed a carcinogen with limited human studies.
c Expected levels of elements in soil from reference 20.
d A child who exhibits pica behavior -- ingests non-nutritive substances such as soil.
f Spiked sample not within control limits.
g The limit of detection.
h ND = not detected.
i Data from reference (4).
j eg Aroclor-1248, -1254, -1260; 2,4',6-trichloro-1,1'-biphenyl; 2,3, 3',6'-tetra..., 2,2',3,5'-tetra...; 2,2',3, 4-tetra...; 2,2', 4,5'-tetra...; 2,3',4', 5-tetra...; 2,2',6,6'-tetra...; 2,2', 3,5,5'-penta...; 2,3,3',4',6-penta...; 2,2',3,4',5'-penta...; 2,2',3,3',6'-penta...; 2,3',4, 4',5-penta...; 2,3',4,5,5'-penta...
Lead is present near the surface (2-4 feet down) of the battery acid pit (1100-1) at levels that increase sharply as the surface is approached. The proximity to the surface of high levels of lead in the backfill is evidence that the site may have been contaminated with more lead after it had been backfilled. For this reason, absence of surface sampling at the battery acid pit could be a significant data gap. DOE suggests that the concentration gradient is evidence that the lead is unlikely to be a groundwater contaminant in the near future (3).
Scattered about the Horn Rapids Landfill were depressions in which lead was found in surface orsubsurface sampling. Most (>80%) had lead at levels below 30 ppm. In the sparsely samplednortheastern corner of the landfill, there were two adjacent surface hits, one at 102 ppm and oneestimated at 482 ppm. A boring from this region contained lead estimated at 854 ppm 4 feetbelow the surface. According to the record of decision, soil in this portion of the landfill is notslated for removal but will be covered by a cap of 24 inches of soil (9).
Polychlorinated biphenyls (PCBs) were reported at concentrations sufficient to justify furtherevaluation at the rainwater pool and in 8 of 10 samples taken 0-1.5 feet below the surface in thesouth-central Horn Rapids Landfill (4). Based on comparison of the retention time to that ofstandards, DOE identified the mixture of PCBs as Aroclor 1248 (3,4). However, identification ofthe specific chemicals classed as PCBs is not always straightforward (see references cited in thesection on Toxicological Implications). PCB-contaminated soil at both the landfill and the rainwater pool will be removed to off-site disposal facilities before the landfill is capped with soil (9).
Friable asbestos was reported, but not quantitated, at the landfill. During remediation, a layer of24 inches of soil will be applied to the landfill to prevent dispersal of asbestos fibers as fugitivedust (9).
There was no analysis of the soil samples for nitrate, a contaminant in groundwater.
Although the 1100-Area is currently under DOE's controlled access and will remain so until theyear 2018, future use is under debate (6). Some of the public advocates unrestricted use for the1100-Area (6). DOE representatives prefer that the 1100-Area remain zoned industrial in thefuture but did not formally commit to restrict future land use (see Appendix A) (p 7-40 in ref. 4,7). Multiple comparison values were chosen to reflect potential exposure levels that could occurdepending on whether the area is developed for residential use or remains industrial.
Surface Water and Sediment
No permanent surface waters or seasonal streams are within EM-1, EM-2, or EM-3, althoughthere may be some seasonal streams in IU-1.
Groundwater - Monitoring Wells
Groundwater information is available for the on-site operable units EM-1, EM-2, and EM-3, butnot for IU-1 (4,8). Information for operable unit IU-1 was addressed as a LFI/FFS in anaddendum to the Remedial Investigation and Feasibility Study of the EM-1 Operable Unit in thethird quarter of FY 1993 (8). The addendum and the record of decision, signed in September1993, gave no groundwater data for IU-1 (8,9). The potential for the public to come in contactwith contaminants that might be in groundwater under the operable units of the 1100-Area willbe addressed in the Pathways section of this document. For the present, it is sufficient to pointout that groundwater under Operable Unit IU-1 or under the Horn Rapids Landfill of Operable Unit EM-1 is not moving towards sources of potable water used by the public.
The local unconfined (lower) and confined (upper) aquifers within and near EM-1 were sampled from 16 wells and analyzed during the Phase I Remedial Investigation. During the Phase II Remedial Investigation (1991-2), seven more wells were drilled and sampled (4).
Figure 5 shows the locations of the monitoring wells. Comparing Figure 5 with Figure 2 showsthat wells number 1 and 3 are within Operable Unit EM-2, and Well Number 17 is withinOperable Unit EM-3. Thus, there are data for all groundwater moving toward Richland.
Data from the Final Remedial Investigation/Feasibility Study summarized six sampling roundsfrom March 1991 through March 1992. The samples were analyzed for Washington Stateprimary and relevant secondary drinking water standards, RCRA groundwater monitoringparameters, general chemistry parameters, Contract Laboratory Program organic and inorganicparameters, coliform bacteria, and radiochemical parameters (4).
Results of the sampling and analyses are shown in Table 3. Soluble arsenic (with similarconcentrations in filtered and unfiltered samples) was detected throughout the lower, unconfinedaquifer, especially near 1100-2 and 1100-3. Arsenic is not a product or byproduct of current orpast activities on the Hanford Nuclear Reservation. The EPA suggests that its presence in thegroundwater is likely due to leaching from the basaltic soil because the soil contains too littleiron to bind the arsenic (21). Arsenic is listed in this table although ATSDR does not assume itto be a contaminant generated by DOE. It was found at levels sufficiently high in groundwater tojustify further evaluation in this assessment.
Lead was present, although not above its MCL, near 1100-2, 1100-3, and the Horn RapidsLandfill. Trichloroethylene and nitrate were at the boundary of Horn Rapids Landfill. Neithersubstance was detected above comparison value in groundwater moving toward sources ofpotable water used by the public. Antimony and manganese were widely distributed but not inconcentrations sufficient to justify further evaluation in this health assessment.
Chromium, primarily insoluble, was at a sufficient concentration in samples (Monitoring Wells Numbered 20 and 21) from the plume from Siemens (Advanced Nuclear Fuels) and the Horn Rapids Landfill to justify further evaluation in this assessment (4). At another location, well upgradient of the plume under the landfill, a sample taken in the summer of 1992 from Monitoring Well Number 3 (near 1100-1 and 1100-4) contained 2,810 ppb chromium (22). The level of chromium downgradient of this well, in Well Number 17 (under EM-3) did not indicate migration of chromium contamination toward municipal water at levels substantially above comparison values. The chromium oxidation state was not reported for either location, although the high proportion of insoluble chromium and the neutral pH of the water suggests the metal is predominantly in the chromium-III rather than chromium-VI oxidation state. The public health significance of the chromium oxidation state will be discussed in the section on toxicological implications.
|Contaminant||Well Nos.a||Concentration (ppb)b||Date||Cancer Class and |
|Trichloroethylene (TCE)||12,13,14,15||56-82||3/91-3/92||3.0 (B2c, EPA)||CREG|
|Aldrin||All wells||0.05d-0.06d||3/91-3/92||0.002 (B2, EPA)||CREG|
|Di(2-ethylhexyl)phthalate (DEHP)||All wells||10d-40d||3/91-3/92||3 |
|Total PCBse||All wells||4.5d||3/91-3/92||0.005 |
|Arsenic||All but #21 |
5-8, 12, 18
|0.02 (A, EPA)||CREG|
| RMEG |
| None (B2, EPA) |
|10,000|| MCL |
(to protect infants)
a Wells 9 and 21 tapped the upper, confined aquifer; water level in well 17, said to tap the confined aquifer, fluctuated with the level of the unconfined aquifer; all others tapped the lower, unconfined aquifer.
b Data from reference 4 unless otherwise stated.
c EPA considers the weight of evidence for carcinogenicity of TCE is between C (possible human carcinogen) and B-2 (probable human carcinogen). TCE caused cancer in rodents, but evidence for human carcinogenicity is equivocal.
d The limit of detection.
e Aroclor-1016, -1221, -1232, -1242, -1248, -1254, -1260.
f Unfiltered samples are not consistently higher than filtered samples (much of substance is dissolved).
g Contract-required detection limit > reported value > instrument detection limit.
h Environmental CrVI persistence is unlikely.
i Unfiltered samples had levels several times those of filtered samples (much of substance is insoluble).
j From reference 22.
k Sample pH was 1.6.
Ethylene glycol was assayed in monitoring wells near 1100-3 and 1100-4, but the detectedconcentrations do not justify further evaluation in this public health assessment.
Groundwater contamination is mainly near the landfill. Except for chromium in MonitoringWell Number 3 (but not in Number 17) and naturally occurring arsenic, substances detected nearRichland municipal wells are below or marginally above comparison values (Table 3).
Air samples were collected April 11, 1990 upwind and downwind of suboperable units 1100-1,1100-3, and the Horn Rapids landfill. Tetrachloroethylene, 1,1,1-trichloroethane, carbontetrachloride, trichloroethylene, toluene, and octane were found downwind at concentrations thesame as or lower than those upwind (3). Total polycyclic aromatic hydrocarbons (PAHs) werefound at 6 micrograms per cubic meter (µg/m3) downwind of 1100-3, twice the concentration ofthose found upwind (3). The Occupational Safety and Health Administration (OSHA)permissible exposure limit for coal tar pitch volatiles, including PAHs, is 200 µg/m3 (23). ATSDR derived a comparison value of 5 µg/m3 for general public exposure by adjusting OSHA'spermissible exposure limit for the greater duration and frequency of nonoccupational exposureand applying an uncertainty factor of 10 to allow for possible increased sensitivity of the generalpublic relative to healthy workers. Because total airborne PAHs near 1100-3 exceeded thiscomparison value, they will be further evaluated in this assessment.
Few environmental data are available for off-site contamination related to the 1100-Area.
No data were available on contaminants that may be in surface or subsurface soil off site.
Surface Water and Sediment
The potential for contaminants from the 1100-Area to reach the Columbia River will bediscussed in the Pathways section of this document.
Groundwater - Municipal and Private Wells
ATSDR scientists reviewed Richland city well data for contaminants from the 1100-Area. Analyses of composite samples taken in 1987 and 1988 from the North Richland Wellfield wereavailable prior to the remedial investigation (18). The results of analyses of samples taken fromthe North Richland and Duke wellfields from 1991 through 1994 were made available to ATSDRin 1994 (24,25).
Although the presence of "nitrates, sodium, and sulfate . . . in Richland's well water" was a causefor placement of the 1100-Area on the NPL (2), the concentrations of these substances in theNorth Richland and Duke wellfields were insufficient to justify further evaluation in this publichealth assessment (18,24,25). Nitrate was detected in Duke Wellfield, 1 mile south southeast ofthe 1100-Area boundary, at 8,000 ppb, and in the North Richland Wellfield at 200 ppb (24,25). Both concentrations are below the comparison value of 10,000 ppb, selected by ATSDR toprotect infants. The North Richland and Duke wellfield supply 15% and 3-7%, respectively, ofRichland's water. Nitrate is below the 200 ppb limit of detection in the Columbia River, whichsupplies 70% of Richland's water (25).
Sulfate was not detected in either wellfield, and sodium was 23 and 5 ppm in the North Richlandand Duke wellfields, respectively (24,25). The 1100-Area groundwater contaminants,trichloroethylene, lead, arsenic, and chromium, were reported less than 0.5 and 2, 10, and 10 ppb,respectively, in both wellfields (24,25).
Twelve private wells used for domestic consumption are south of the 1100-Area and within3,000 feet of the wells in the Duke Wellfield (15). The six northernmost wells are shown inFigure 5. Other private wells tapped for household use were located in two regions within thecity of Richland. Both of them are at least 8 miles south of the 1100-Area and across the YakimaRiver (12,16). Groundwater flow under the 1100-Area is eastward and northeastward toward theColumbia River, not south to the Yakima River. ATSDR investigators believe these southernprivate wells unlikely to be contaminated by substances in 1100-Area groundwater.
No data were available on levels of any contaminants in the ambient air off site. In the absenceof data, ATSDR performed worst-case modeling. Agency scientists estimated the maximal off-site concentration of PAHs to be less than 0.4 µg/m3. As described in the section on ambient aircontaminants on site, ATSDR derived a comparison value of 5 µg/m3 for general publicexposure to PAHs.
The downwind station that detected 6 µg/m3 PAHs on site was 250 feet from the presumedsource of air contamination, 1100-3 (3). As the volume of an airborne contamination plumeexpands, the concentration of contaminants will be reduced proportionately. For example, if thePAH plume's width, height, and length all doubled, the concentration would be reduced to 1/2 X1/2 X 1/2 X 6 µg/m3, or 0.8 µg/m3. The nearest access to the public downwind and off site isabout 4,000 feet farther away from the downwind station (immediately outside the EM-3Operable Unit's eastern border) (3). If the plume lengthened by 4,000 feet but did not increase inwidth or height the PAH concentration at that point could maximally reach 250/(4,000+250) X 6µg/m3, or 0.4 µg/m3. Because the lengthening plume would probably also expand in width andheight, the PAH concentration 4,000 feet from the downwind station would probably be lowerthan 0.4 µg/m3.
Using the derived comparison value, ATSDR investigators do not consider the level ofcontamination of off-site ambient air likely to be sufficient to justify further evaluation.
Toxic Chemical Release Inventory
Under Section 313 of the Emergency Planning and Community Right-to-Know Act (SARA,Title III), manufacturers are required to report to the EPA annually if they have released into theenvironment (routinely or accidentally) any of more than 300 toxic chemicals. Section 313authorizes EPA to maintain the data in a computerized database known as the Toxic ChemicalRelease Inventory. Manufacturing facilities (as defined in the Standard Industrial Classificationcodes 20-39) that have 10 or more full-time employees and that manufacture or use a Title III-listed chemical in an amount greater than its specified threshold for manufacture, import,processing, or other use during any calendar year are required to estimate their annual releases ofsuch toxic chemicals into the air, water, and land. The database is available to federal and stategovernment officials as well as to the public.
ATSDR investigators searched the Toxic Chemical Release Inventory database for toxicchemical releases to the soil, water, and air from facilities in Benton County, Washington,including the Hanford Nuclear Reservation, for the reporting years 1987 through 1990. TheHanford Nuclear Reservation was listed as a single entity, but ATSDR used information fromDOE to distinguish among the releases from four NPL sites (26). In particular, releases from the1100-Area could be identified. Table C-1 through Table C-4 summarize reported releasesgreater than one pound. Table C-1 lists releases to soil from DOE and industries of BentonCounty. None of the releases to land reported by DOE originated from the 1100-Area. From1987-1990, the DOE released from Hanford's other NPL sites an assortment of chemicals,including a total of approximately 2,300 tons of sulfuric acid, sodium hydroxide, and their salt(sodium sulfate) to the soil. Approximately 2.3 tons of nitric acid was reported during thisperiod. Sodium hydroxide was also released by other industries in Benton County. Otherreleases to soil included fertilizer components, such as ammonia and ammonium nitrate.
Smaller releases of sodium hydroxide and sodium sulfate from the Hanford Nuclear Reservationinto surface water were reported during this period, but none from the 1100-Area (Table C-2). The largest chemical release to surface water from private industry in Benton County was 8 tonsof sodium hydroxide during 1987.
In 1987, the 1100-Area was the source of 1 pound of acetone, 7 pounds of methyl ethyl ketone, 2pounds of sulfuric acid, and 13 pounds of 1,1,1-trichloroethane released into the air (see theshaded rows in Table C-3). Of the air releases reported for the remainder of Hanford, the largest,more than 8 tons of carbon tetrachloride from the 200-Area, took place over the course of 1987. Hanford Nuclear Reservation also was the source of about 5 tons of other volatile organicsolvents, including acetone, methyl ethyl ketone, tetrachloroethylene, Freon-113, and 1,1,1-trichloroethane, during 1987. Nine to 10 tons of ammonia were released during 1987 and 1989,and a ton and a half of chlorine was released during 1987. The largest recent release was about23.5 tons of nitric acid during 1990.
The Hanford Nuclear Reservation was not the largest source of chlorine and ammonia released tothe air in Benton County -- during the reporting period, other sources released 15 tons of chlorineand more than 2,500 tons of ammonia. But all other Benton County industries reported lessnitric acid and volatile organic compounds than the Hanford Nuclear Reservation released intothe air during 1987 through 1990 (see Table C-4).
The Toxic Chemical Release Inventory may not be the best way to accurately representcontributors to contamination of the Hanford region. Limitations of the Toxic Chemical ReleaseInventory database include unreported or unknown releases or spills, contamination prior to1987, sources not required by law to report releases, and inaccurate estimations.
Quality assurance procedures for soil sampling and analysis were outlined by WestinghouseHanford Company in the DOE Work Plan for the Phase I Remedial Investigation (18). ATSDRinvestigators were unable to find data quality reports for soil analysis data. The WestinghouseHanford Company Office of Sample Management provided validated results for groundwatersampling round 5 (March 1991) and partially validated results for round 6 (June 1991). Theremaining groundwater analytical data were validated by the U.S. Army Corps of Engineersusing current EPA Contract Laboratory Program guidelines (4,27).
Because soil sampling at EM-1 was nonrandom, but chosen from locations DOE believed mostlikely to be contaminated by vehicle maintenance or waste disposal activity, ATSDR cannotassume the data in Table 2 are representative of overall on-site contamination. Given the basis ofsample selection, the sampled areas probably represent higher than typical soil contamination --i.e., they may be hot spots.
As discussed in the references for the Toxicological Implications section of this document,technical details in the standard methods used for PCBs may result in some uncertainty regardingtheir identification. The soil concentrations and the limits of detection for PCBs listed in Table 2are for the total of all PCB species and mixtures determined in a sample. For example, if thelimit of detection for Aroclor-1248, Aroclor-1254, and Aroclor-1260 was 0.09 ppm for each ofthe commercial mixtures reported in a sample, than the total concentration of these PCBs whichcould have escaped detection in the sample would have been 0.27 ppm.
As in the case of soil, groundwater concentrations and limits of detection were listed in Table 3for total PCBs. Because the limit of detection for each of the commercial mixtures was aboveATSDR's CREG, the total that could have escaped detection is almost 1,000 times the CREG. The detection limits for aldrin and DEHP were also above comparison values in groundwater.
Sulfate at 3,300,000 ppb appeared once at pH 1.6 in Well Number 18. This concentration ofsulfate was at least 50 times higher than the concentration in any other sample. The combinationof a high concentration of sulfate with a low pH is essentially sulfuric acid, used by DOE topretreat sample bottles when a preservative was needed. Such a low pH, if representative oflocal groundwater, would have leached alkaline earth metals (magnesium, calcium, and the like)from the soil. The result was found in only one round out of six in this well, and not in any ofthe six rounds in nearby Well 8A. The presence of normally low levels of alkaline earth metalsin the 1 high sulfate sample out of 12 from 2 adjacent wells strongly suggests that the highsulfate concentration resulted from sample contamination, probably due to inadvertent use of apreservative-treated bottle (22).
With those exceptions, ATSDR relied on information provided by DOE and its contractor,Westinghouse Hanford Company, and assumed that adequate quality assurance and qualitycontrol measures were followed with regard to chain of custody, laboratory procedures, and datareporting. The validity of the analysis and conclusions drawn in this public health assessmentdepend on the completeness and reliability of the referenced information.
No physical hazards were observed within the 1100-Area other than those associated with normaloperations of a maintenance area. Sites of potential contamination were well delineated andposted. Areas of potential soil contamination were marked with chains.
ATSDR investigators have not found contaminants in 1100-Area soil that could present anexplosion hazard to DOE visitors or employees in the present or to the public in the event offuture commercial or residential development. At EM-3, gasoline tanks were removed and thesoil was remediated in 1991. The Horn Rapids Landfill was used for construction and industrialwastes, not household wastes; no methanogenic substances were buried in this landfill. Inaddition, ATSDR scientists observed that wastes are buried by coarse soil of a texture betweensand and gravel and containing little or no organic matter. This soil is unlikely to trap lighter-than-air substances such as methane. The landfill was extensively monitored for soil gases todelimit the groundwater plume migrating beneath. The process used an organic vapor monitor. The only positive readings were near paint cans. No explosive levels of any substance werefound. No methane gas was found (4).
The 1100-Area is currently patrolled by the DOE-contracted security force, and access is well controlled. While portions of the 1100-Area are not completely restricted, the sites of concern are not located in areas where casual trespassing would be a likely problem.
To determine whether humans are exposed to contaminants migrating from a site, ATSDR staffmembers evaluate the environmental and human components that lead to human exposure. Thisevaluation or pathways analysis consists of five elements: source of contamination;environmental medium in which contaminants may be present or into which they may migrate;point of human exposure such as a private well; route of human exposure such as ingestion,inhalation or dermal contact; and receptor population (people who are exposed or potentiallyexposed).
ATSDR identifies exposure pathways as completed or potential. For a completed pathway toexist, all of the five elements must be present to provide evidence that exposure to a contaminanthas occurred in the past, is occurring, or will occur in the foreseeable future. A potentialpathway indicates that at least one of the five elements is missing but could exist. Potentialpathways indicate that exposure to a contaminant could have occurred, could be occurring, orcould occur in the future. Pathways are eliminated when at least one of the five elements ismissing and will never be present.
Past, present, and future exposure pathways that may present public health hazards are discussedin this section.
There was no identification of completed exposure pathways at the 1100-Area by whichcontaminants in soil or groundwater could reach the public.
Because security measures restrict public access to EM-1, including the suboperable units 1100-1through 1100-4, 1100-6, the Horn Rapids Landfill, EM-2, and EM-3, the public has notpreviously had and does not currently have opportunity for contact with soil contamination onsite. Similarly, the public does not have access to Operable Unit IU-1. This restricted accesswill continue as long as the property remains under DOE control. The time frame forremediation and release of DOE's Hanford property extends to the year 2018 (6). Although DOEstated "The 1100-Area . . . is to remain zoned industrial in the future," there is no formalcommitment to restrict land use beyond the year 2018 (see Appendix A) (p 7-40 in ref. 4, 7). There are some among the public that prefer unrestricted use after that time (6).
ATSDR found no evidence of completed pathways for worker exposure in the 1100-Area.Because the mission of the 1100-Area is support and vehicle maintenance activities, there is littleneed for DOE employees and contractors working in the 1100-Area to engage in frequent contactwith contaminated soil in the course of their duties. During remediation, ATSDR assumes thatproper OSHA procedures will be used.
The flow of ground- and surface water from contaminated parts of the 1100-Area equipmentmaintenance units is illustrated in Figure 5.
There is no completed pathway by which the public could have come in contact with nitrate- andTCE-contaminated groundwater migrating under the Horn Rapids Landfill in the past or bywhich the public could come in contact with such water now. There are no known private ormunicipal wells that are or have been used to supply drinking water (3,4). As for the near future,there are no plans for municipal or private drinking water wells that might intercept the plume ofcontamination to the east and northeast of the landfill as the plume extends to the ColumbiaRiver in the region of the 300-Area. The 300-Area, another NPL site of the Hanford NuclearReservation, does not draw drinking water from on-site wells. Drinking water for the 300-Areacomes from the Columbia River (11,28). The 1100-Area itself is supplied potable and fire-control water by the city of Richland (5,12). Richland's municipal wells are 2 miles south-southeast of the landfill, out of the migration path of this plume (3,4).
No completed pathway exposes the public using Richland's municipal water system to anycontaminants in the southern portion of the EM-1 Operable Unit, including 1100-1 through1100-6; the EM-2 Operable Unit; and the EM-3 Operable Unit. The Duke and Columbia wellsare on Saint Street, a Richland street that passes a half mile south of the 1100-Area and extendsdue east to the Columbia River (see Figure 5). Contaminants in the 1100-Area were not found atconcentrations of concern in water from the Duke Wellfield. This may be because the wells aretoo far south to be in the migration paths of contaminants under EM-1, EM-2 or EM-3. TheNorth Richland Wellfield is due east of these sources of contamination and could be in themigration paths. However, water from the Columbia River is pumped into the wellfield fasterthan the city of Richland pumps water out for municipal use (25). These relative rates ofpumping probably explain why the nitrate concentration in the water from these wells resemblesthat in the Columbia River more than that in the groundwater from the Duke wells (25). Moreover, 70% of Richland's gravity feed water distribution system is supplied directly from theColumbia River, further diluting groundwater drawn from the wells before it reaches the public(12).
No completed pathway exposes Richland's residents using water from private wells for domesticpurposes to contaminants in the southern portion of the EM-1 Operable Unit, including 1100-1through 1100-6; the EM-2 Operable Unit, and the EM-3 Operable Unit. Twelve private wells arewithin an area with its north side 4,000 feet south of 1100-1 (15). Six of these are shown inFigure 5 near the Duke and Columbia wells. The absence of 1100-Area contaminants in Dukewells may be because the wells are too far south to be in the pathway of contaminatedgroundwater movement. The same logic applies to the six private wells shown in Figure 5. Theother six wells are still farther south, out of range of the map.
Other private wells tapped for household use were located in two regions within the city ofRichland. Both of them are at least 8 miles due south of the 1100-Area's operable units andacross the Yakima River (12,16). The flow of groundwater under the 1100-Area is eastwardtoward the Columbia River, not southward to this part of the Yakima River. ATSDR does notconsider that these wells could form part of a completed pathway by which the public is likely tobe exposed to 1100-Area contaminants.
Under federal ownership, the land on the Hanford Nuclear Reservation is not used for residentialor agricultural purposes, and domestic wells are not tapping groundwater in the vicinity ofOperable Unit IU-1. This situation is unlikely to change before the year 2018. Because themovement of water underground (groundwater flow) tends to be downhill, people living orfarming on the other side of the Rattlesnake Hills are unlikely to draw groundwater that might becontaminated by IU-1 soil. The downhill slope on the IU-1 side of the hills extendsapproximately in the direction of the 400-Area (shown in Figure 1). Groundwater flow fromunder IU-1 is unlikely to pass close to sources of potable water used by Richland. Thus,although environmental data were not available for Operable Unit IU-1, pathway considerationsmake exposure of the public to any IU-1 groundwater contaminants unlikely as long as controlremains under DOE. DOE has not committed to formal restrictions in its transfer of propertyafter the year 2018 (p 7-40 in ref. 4, 7).
The selected remediation alternative will treat three types of contaminated soil. Soilcontaminated with PCBs (at the Rainwater Pool and the south central part of the Horn RapidsLandfill) will be disposed of off site (9). Discolored soil at 1100-6 will be incinerated off site(9). The surface of the Horn Rapids Landfill, including the part contaminated with lead, will becovered with 24 inches of soil to prevent friable asbestos from becoming airborne (9). Thecleanup standards in the record of decision are chosen assuming industrial use at the Horn RapidsLandfill and possible residential use at the Discolored Soil Site (1100-6), the Rainwater Pool,and other operable and suboperable units that are not selected for remediation (9). A DOErepresentative believes that in the future, the 1100-Area is likely to be used for offices, researchfacilities, or industry (7). Some people in the community want the 1100-Area to becomeavailable for unrestricted use in the year 2018 (6). DOE is currently not considering deed and excavation restrictions to prevent residential development (p 7-40 in ref. 4).
Disturbance of soil during development after 2018 could blur the distinction between surface andsubsurface contaminants. Excavation could cause all soil to have the potential of becomingsurface soil. For example, as building foundations are laid in the years beyond 2018, clumps ofsoil containing lead at 266 ppm (now 1.5-2.0 feet below the surface at 1100-1) or 854 ppm (now4 feet below the surface in the northeastern corner of the Horn Rapids Landfill), could be gougedout and used to level surfaces for parking areas, roads, parks, and possibly houses (3,4). Thoseexposed by ingestion, inhalation, or dermal contact with the soil after the year 2018 couldinclude unknown numbers of construction workers, office park employees, and possiblyresidents working and living in the area during and after development of the 1100-Area. Thus,after 2018, workers may be exposed by ingestion, inhalation, and dermal contact as they excavateand construct office buildings and landscape parks and yards. After 2018, potential office andlaboratory personnel could be exposed by inhalation and ingestion to windborne soil whencommuting or eating outdoors. In the decades to come, in the absence of land use restrictions,resident families could be exposed as they garden or play in backyard soil. The first row ofTable 4 summarizes the potential for this type of pathway.
|PATHWAY NAME||EXPOSURE PATHWAY ELEMENTS||TIME|
|POINTS OF |
|ROUTES OF |
|Surface Soil||Equipment |
and Isolated (IU)
|Unknown Number |
of Construction &
|After 2018 |
(During & after
|32,000 in Richland||Unlikely Because |
with River Water
ATSDR considered two pathways by which contaminated groundwater might potentially reachwater taken in by the public through ingestion, inhalation, and dermal contact (see Figure 5).
First, ATSDR scientists considered whether groundwater contaminants from the EM-1suboperable units in the southern half of the 1100-Area and from the operable units EM-2 andEM-3 could migrate eastward to the North Richland Wellfield and expose Richland residents(Groundwater southeast in Table 4). Exposure to hazardous concentrations of contaminants bythis pathway is unlikely because contaminants in groundwater migrating toward this wellfield arediluted by the river twice. The first dilution occurs when water from the Columbia River ispumped into the wellfield, and a second dilution occurs when 15 volumes of water from thewellfield are mixed in Richland's distribution system with 70 volumes of water from the riverand an additional 15 volumes from other sources. ATSDR scientists considered whether thispathway could become a health threat in the future if the operators of Richland's water systemshould cease to pump water into the North Richland Wellfield from the Columbia River fasterthan the system would draw water from the wellfield for municipal use, thus inadequatelydiluting groundwater with river water. This could happen if municipal demand increases due, forexample, to a population increase or to increased demand from parts of Hanford released by DOE.
The nitrate concentration in the wellfield could serve as a warning indicator in such a case. Thepresent concentration of nitrate in water from the North Richland Wellfield more closelyresembles the nitrate concentration in the Columbia River than that of wells further south thatdraw groundwater (and that are below the comparison value selected by ATSDR to protectinfants). A rising nitrate concentration in the North Richland Wellfield would indicate that afalling proportion of Columbia River water in the wellfield might be insufficient by itself todilute contaminants that might be in groundwater.
ATSDR investigators then considered groundwater chromium, found in Well Number 3, couldpotentially reach the public by this pathway. The chromium plume has been diluted almostfiftyfold as it spread from Well Number 3 to Well Number 17 (see Table 3 and Figure 5). Asdiscussed above, the chromium would be further diluted by river water pumped into the NorthRichland Wellfield and by water from the river and other sources mixed with wellfield water inthe city distribution system. Moreover, as will be explained in the Toxicological Implications section, environmental chromium is unlikely to persist in a hazardous form.
ATSDR scientists consider it highly unlikely that the second pathway (Groundwater Northeast inTable 4) will present a hazard. By this pathway, groundwater contaminants migrating under theHorn Rapids Landfill would reach the Columbia River and thence the city water supplies forRichland, Pasco, and Kennewick. The flow of the Columbia River averages 120,000 cubic feetper second (17). Should groundwater contaminants under the Horn Rapids Landfill reach theColumbia River, they would be quickly diluted by the river's rapid flow. The contaminants(from under the Horn Rapids Landfill) are unlikely to be detectable more than a few yards fromtheir point of entry into the river. They are unlikely to threaten the river's current Class A(excellent) status.
If after the year 2018, land near the paint and solvent pit (Suboperable Unit 1100-3 of EM-1,which is not selected for remediation in the record of decision) is developed for residential use,persons who then build houses within 500 feet of that site could be exposed to concentrations ofPAHs above the comparison value developed by ATSDR. Past, current, or future employees ofthe DOE or its contractors would have been or would be exposed below the OSHA permissibleexposure levels for occupational exposure and so are not included in this pathway. This potentialpathway could be completed only if, in the absence of restrictions on land transfers that couldtake place in the year 2018, the current equipment maintenance areas are developed for residential use.
A tripartite approach is used to assess the public health implications associated with a site. First,ATSDR scientists address the toxicological implications in a discussion of health effects thatmight occur in people exposed to specific contaminants. Second, they evaluate state and localhealth databases for evidence that such health effects have occurred. And finally, the Agencyaddresses the community's concerns about site-related health issues. ATSDR staff membersbelieve that all three approaches are important to the eventual development of acceptablesolutions to site-specific public health problems.
A release of a hazardous waste does not always result in exposure. People are exposed to anonradiological contaminant such as those identified in the 1100-Area only if they come incontact with it; exposure may occur by breathing, eating, or drinking a substance containing thecontaminant or by skin contact with a substance containing the contaminant. Several factorsdetermine the type and severity of health effects associated with exposure to a contaminant. Such factors include the exposure concentration (how much); the frequency and/or duration ofexposure (how long); the route of exposure (breathing, eating, drinking, or skin contact); and themultiplicity of exposure (combination of contaminants). Moreover, people can be exposed to anenvironmental contaminant by more than one route of exposure. Once exposure takes place,characteristics such as age, sex, nutritional status, genetics, lifestyle, and health status of theexposed individual influence how the individual absorbs, distributes, metabolizes, and excretesthe contaminant. Together, those factors and characteristics determine the health effects that mayresult from exposure to a contaminant.
ATSDR scientists consider the previously described physical and biologic characteristics whendeveloping health guidelines. Toxicological profiles prepared by the Agency's scientistssummarize chemical-specific toxicologic and adverse health effects information. Healthguidelines, such as ATSDR's minimal risk level (MRL) and EPA's reference dose (RfD) andcancer slope factor (CSF) are included in the toxicological profiles. Those guidelines are used byATSDR public health professionals to determine an individual's potential for developing adversenoncancer health effects and/or cancer from exposure to a hazardous substance.
Health guidelines provide a basis for comparing estimated exposures with concentrations ofcontaminants in environmental media (soil, air, water, and food) depending on who might beexposed and the length of the exposure. An MRL is defined as an estimate of the daily humanexposure to a contaminant that is likely to be without an appreciable risk of adverse noncancerhealth effects over a specified duration of exposure (acute, <15 days; intermediate, 15-365 days;chronic >365 days). Oral MRLs are expressed in units of milligrams per kilogram per day(mg/kg/day). MRLs are not derived for dermal exposure. The method for deriving MRLs doesnot include information about cancer; therefore, an MRL does not imply anything about thepresence, absence, or level of cancer risk. An EPA RfD is an estimate of the daily exposure ofthe human population, including sensitive subpopulations, that is unlikely to cause adversenoncancer health effects during a lifetime (70 years). Noncancer health guidelines are adjusteddownward using uncertainty factors to make them adequately protective of the public health. Therefore, the health guidelines should not be viewed as a strict boundary between what level istoxic and what level is nontoxic. For cancer-causing substances, EPA has established the CSF asa health guideline. The CSF is used to estimate the number of excess cancers maximallyexpected from exposure to a contaminant.
To link a site's human exposure potential with health effects that may occur under site-specificconditions, ATSDR investigators estimate human exposure to site contaminants from ingestionand/or inhalation of different environmental media. The following relationship is used todetermine the estimated exposure to the site contaminant:
- ED = (C x IR x EF) / BW
ED = exposure dose (mg/kg/day)
C = contaminant concentration
IR = intake rate
EF = exposure factor
BW = body weight
ATSDR uses standard intake rates for ingestion of water and soil. The intake rate for drinkingwater is 2 liters per day (L/day) for adults and 1 L/day for children. For incidental ingestion ofsoil, the intake rate is 100 mg/day for adults, 200 mg/day for children, and 5,000 mg/day forchildren with pica behavior (repeated ingestion of non-nutritive substances). Standard bodyweights for adults and children are 70 kg and 10 kg, respectively. The maximum contaminantconcentration detected in a specific medium at a site is used to determine the estimated exposure;use of the maximum concentration results in an evaluation that is most protective of human health. When unknown, the biological absorption from environmental media (soil, water, etc.) is assumed to be 100%.
People may be exposed to more than one contaminant from a site. Data on the health effects ofexposure to multiple contaminants are very limited. Those effects can be additive, synergistic(greater than the sum of the single contaminant exposures), or antagonistic (less than the sum ofthe single contaminant exposures). Also, simultaneous exposure to contaminants that are knownor probable human carcinogens could increase the risk of developing cancer. In most cases, thereis insufficient information about the effect of mixtures of contaminants. ATSDR's evaluation ofexposures in this public health assessment is limited to individual contaminant exposures;multiple exposures have not been evaluated.
Sometimes several potential pathways exist by which site contaminants in could reach the public. Multiple pathways may complicate the assessment of potential health effects because they couldincrease an individual's exposure to substances.
At the 1100-Area of Hanford, the limiting factor affecting exposures that could havetoxicological implications is the existence of or the potential for a pathway by which peoplecould come in contact with contaminants. For this reason, some pathway-specific informationpreviously discussed in the Pathway Analyses section of this document will be repeated here incases where such information could aid in the understanding of toxicological implications.
Past, Current, and Future Implications to the Year 2018
No adverse health effects are expected from past, current, or future exposures to 1100-Area air orsoil contaminants through the year 2018. This is because no families live or have lived in thisarea since the beginning of activities that resulted in the present contamination. Thus, noresident family is or has been exposed to any air or soil contaminants. This situation is likely tocontinue until the federal government transfers the land in the year 2018. Given the nature ofwork performed by 1100-Area employees (vehicle maintenance and other support functions), ithas been and continues to be unlikely for employees to have frequent and lengthy contact withsoil. Workers are unlikely to be at risk from air contaminants because contaminants were notidentified at concentrations above OSHA standards (23). Remediation workers could havegreater exposure to soil contaminants. ATSDR assumes OSHA requirements for workerprotection against contaminated media will be met during remediation.
Future Implications of an 1100-Area Redeveloped After the Year 2018
The future uses of the 1100-Area are currently under debate, and this area may be open to publicuses beyond the year 2018 (6). Although DOE stated "The 1100-Area . . . is to remain zonedindustrial in the future," there is no formal commitment to restrict future land use (see AppendixA) (p 7-40 ref. 7). There are some among the public that prefer unrestricted use (6). To beprotective of public health, ATSDR has reviewed the toxicological implications that would existif this area were developed for residential, commercial, and industrial use by the public.
Lead -- ATSDR does not have a comparison value for lead. Under current and pastnonresidential land use, the concentration of lead in soil on site (as high as 482 ppm in the top 6inches or 854 ppm 4 feet below the surface at the northeastern corner of the Horn Rapids Landfilland 266 ppm 2 feet below the surface at the battery acid pit) is not harmful to public healthbecause the public did not and does not come in contact with the soil (3,4). As long asnonresidential use continues, no harm to public health can come from lead-related datashortcomings. Two examples of such data inadequacies are (1) estimated values for two highlead concentrations in the sparsely sampled northeastern Horn Rapids Landfill and (2) absence ofsurface sampling at the battery acid pit despite a sharp increase in soil lead concentration as thesurface is approached. Additional sampling could determine whether the estimated soilconcentrations (at the Horn Rapids Landfill and the Battery Acid Pit) reflect widespread leadcontamination. Such widespread contamination by lead in the soil could be harmful for people ifthey moved into an 1100-Area developed for residential use after the year 2018 (29,30). Therelationship between soil lead concentration and the concentration of lead in the blood ofchildren living in an area depends on factors discussed in Appendix D. Under worst-caseconditions, if families who may move into a newly developed 1100-Area have very youngchildren whose average background blood lead concentration is 5 or 6 micrograms per deciliter(µg/dl) -- not considered to be lead-poisoned -- an increase of 6-7 µg/dl to 11-13 µg/dl could besufficient to depress the children's hearing, growth rate, and average IQ (30). If they resided insuch a community, middle-aged men might have a higher average blood pressure (29,30). Officeor industrial employees, who would spend less time in the area and have little contact with thesoil, would not be at risk. For additional information about the toxicological implications oflead-contaminated soil, see Appendix D.
Polychlorinated Biphenyls (PCBs) -- PCBs in the 1100-Area will not present a threat to thepublic when the 1100-Area is released in the future. In the record of decision, soil contaminatedwith PCBs in the Horn Rapids Landfill and the Rainwater Pool will be disposed of off site (9). PCBs are a class of many chemicals. Some of these chemicals are hazardous. The standardanalyses used by DOE may not be adequate to determine whether the PCBs detected in the 1100-Area are the particular chemicals that could cause cancer or harm the immune system, adrenalglands, thyroid glands, central nervous system, skin, eyes, reproductive systems, developingfetuses, and livers of future residents (31,32,33). Removal of the contaminated soil will protectthe public health regardless of the identity of the PCBs present.
Polycyclic Aromatic Hydrocarbons (PAHs) -- ATSDR does not have a comparison value forairborne PAHs because the toxicity of inhaled environmental PAHs has not been adequatelycharacterized. OSHA has set a permissible exposure limit of 200 µg/m3 to protect healthy adultworkers exposed for 8-hour periods (23). These chemicals were identified at the paint andsolvent pit once at 6 µg/m3, which is below the OSHA standard, and therefore not at aconcentration sufficient to threaten the health of 1100-Area employees or employees of futureindustrial and commercial concerns (3,23). Should the 1100-Area become available forresidential development after the year 2018, future residents could include infants, children, theelderly, and the ill, some of whom could be at home more than 8 hours per day. ATSDR cannotdetermine from published toxicity data whether the airborne PAH concentrations would besufficient to harm people who might build their homes within a few feet of this site after the year2018. People currently living off site are unlikely to be exposed to sufficient concentrations ofairborne PAHs to put them at risk of illness.
Di(2-ethylhexyl)phthalate (DEHP) -- DEHP does not pose a threat to the public health now andwill not in the future. DEHP-contaminated soil will be incinerated off site, so future residentswill not be exposed to DEHP in the soil (9). The public will not be at risk if remediation isdelayed or incomplete. In the quantities of soil to which the public might conceivably beexposed orally, by inhalation, and transdermally, DEHP is not likely to cause harmful effects toanyone who might build or live in a home in the 1100-Area in the future. DEHP was found onlyat a surficially stained area of soil (1100-6). Its concentration at this suboperable unit was ashigh as 2.5%, which is much higher than its comparison value (3). It should be noted, however,that DEHP is a commonly used plasticizer that occurs at concentrations as high as 40% infrequently encountered clothing and household items (e.g., rainwear, footwear, upholstery,imitation leather, waterproof gloves, tablecloths, shower curtains, food packaging, floor tiles, andpaint) (34). Small children could suck or chew on such objects. DEHP also is used to plasticizecontainers for transfusible blood (34), to which the public is exposed intravenously uponreceiving transfusions. Aside from gastrointestinal distress from ingestion of 143 but not 71 mgDEHP/kg (which is more than a pica child might ingest daily for a week playing in the soil at1100-6), DEHP has not caused adverse health effects in people (34).
Chromium (Cr) -- The 1250 ppm chromium 14-16 feet below the surface at the Horn RapidsLandfill (3,4) is not now a threat to the public health and is unlikely to become a threat even ifthe land does become residential. There are two reasons for this. First, unless the land is usedfor multistory apartment and office buildings with basement and subbasements, people could notcome in contact with the contamination now or in the future. It is unlikely to be disturbed byhuman activities -- people probably would not dig 14-16 feet in a closed landfill. Second,environmental chromium occurs primarily in two chemical states: chromium-III (Cr-III) andchromium-VI (Cr-VI). The first, Cr-III (comparison values of 2,000 ppm or more), which isenvironmentally very stable, is nutritionally essential for health, and not harmful at soilconcentrations double that maximally reported at the landfill. Even if all the chromium releasedby DOE to the soil were the second form (Cr-VI -- comparison values of 10-4,000 ppm -- ismuch more toxic, especially if inhaled), in deep, airless soil this form is readily reduced to Cr-IIIby sulfur (II) and iron (II) present in the soil; aerobic reduction (in the presence of oxygen) ispossible only when organic substances are present (35-37). In the semidesert climate of easternWashington, the organic content of nonirrigated soil tends to be low. This concentration ofchromium in the soil below the site could be of concern after excavation only in the highlyunlikely possibility that nearly all the chromium had persisted in the environment as Cr-VI for20-50 years.
The 2,810 ppb chromium reported in the groundwater under operable unit EM-2 is not now athreat to public health and is unlikely to become a threat in the future. As discussed in thesections on off-site groundwater contamination and groundwater pathways, groundwatercontaminants in the southern part of the 1100-Area are not migrating towards municipal andprivate wells drawing groundwater rather than river water; analyses of the Duke and Columbiawells have not shown these contaminants above comparison values.
Monitoring well data suggest that contamination in groundwater substantially decreases as itmoves towards the North Richland Wellfield. The concentration of chromium diminished from2,810 to 57.5 ppb in the 600 feet from wells number 3 to 17 (see Figure 5 and Table 3). At thatrate, as the plume extends an additional 260 feet to the western edge of the North RichlandWellfield, its concentration would drop to about 40 ppb, below all chromium comparison valuesfor drinking water. In this wellfield, its concentration would be further diluted by water pumpedfrom the Columbia River. River and groundwater mixed in the wellfield are further diluted inthe Richland distribution system. The final concentration of chromium in Richland tapwater isunlikely to become detectable.
Moreover, the 2,810 ppb chromium would probably be primarily in the more stable, less toxicCr-III (comparison values of 10,000 ppm or more) oxidation state (see above), and thereforebelow its comparison value. Table 3 indicates that where data were given for both filtered andunfiltered samples, unfiltered samples had much more chromium -- i.e., the chromium wasprimarily insoluble. Insoluble chromium is more likely to be Cr-III than Cr-VI. Poorly solubleCr-III tends to have low mobility in ordinary soil because it is adsorbed to clay. Hanford soil isnot clay-like; it is multiple layers of sand and gravel. Suspended Cr-III can be carried along bythe flow of groundwater. Although this does not definitively establish most of the chromium asCr-III, the absence of current chromium contamination and the unlikelihood of future chromiumcontamination in supplies of potable water makes it unnecessary to have definitive informationabout the chromium oxidation state to protect public health.
Arsenic -- People are unlikely to be made ill by ingestion of arsenic, which is present in the1100-Area in soil at concentrations up to 4.2 ppm and in groundwater at concentrations up to 15ppb arsenic. Arsenic in both media is present above its comparison values (3,4). A potentialfuture 1100-Area resident who drank groundwater for a lifetime could maximally average 30 µgarsenic per day, and a child with pica behavior could maximally ingest 21 µg arsenic per dayfrom the soil. Oral arsenic intake as high as 420 µg/day does not cause noncancer effects inhumans, and human cancer has only been observed in studies where prolonged arsenic intakeexceeded 630 µg/day (38). For more information about the toxicity of arsenic, see Appendix D.
Aldrin -- Aldrin was tentatively identified at concentrations sufficient to generate a low increasedcancer risk to potential future residents of the 1100-Area in 4 of 23 soil samples taken from thesurface of the southern and southwestern parts of the paint and solvent pit (1100-2) (3). Thissuboperable unit was not selected for remediation (9). Concentrations ranging from 0.3 to 3.7ppm (about 100 times its comparison value) would be unusually high levels of aldrincontamination if the tentative identification should be confirmed and could present a threat to thepublic health if the area should be developed for residential use after the year 2018 (39). Furtherinformation about the toxicity of aldrin is in Appendix D.
Trichloroethylene (TCE) -- TCE at levels reported in 1100-Area soil and groundwater is not alikely threat to the health of future residents. In soil samples from the 1100-Area, TCE wasfound at levels well below that of concern for public health (3). A TCE-contaminated plume iscurrently migrating northeast towards the Columbia River from the region of the Horn RapidsLandfill (3,4). This plume will be monitored to confirm that the concentration of TCE in thegroundwater is attenuating (or decreasing) as DOE's modeling predicts (9). If attenuation is lessrapid than predicted, and if the 1100-Area should be open to public use in the future, TCE in thisplume could be of concern if people drilled wells into the TCE-contaminated plume but not iftheir water were taken from the river after the plume had reached the Columbia River. TCE istoo volatile to persist in surface water long enough to present a health threat, especially givendilution by the high flow rate of the Columbia River (40). If wells are drilled in the future, datafrom animal studies (but not human studies) suggest the possibility that people drinking thewater for their entire lifetimes might have a very low increased cancer incidence (31). BecauseTCE is volatile, showering and bathing in the well water for their lifetimes might also slightlyincrease their incidence of cancer (31). However, the city of Richland has proposed to supplywater to a future redeveloped 1100-Area, making such lifetime exposures to water from futurewells unlikely (5).
Nitrate -- Nitrate in 1100-Area groundwater is unlikely to cause adverse health effects. Nitrate ispresent at 8 ppm in municipal wells drawing groundwater. This is below the comparison valueof 10 ppm selected by ATSDR to protect infants from methemoglobinemia. This ailment, theoxidation of the oxygen-carrying pigment of the blood, is the critical effect of nitrate ingestion bythose most sensitive among the public -- babies weighing less than 4 kilograms (8 pounds, 13ounces) (31). Methemoglobinemia has not been observed as a result of drinking watercontaining less than 10 ppm nitrate (31). Some 70% of the water in Richland's municipaldistribution system derives from the Columbia River, which contains less than 0.2 ppm nitrate(the level of detection). The considerations that would protect the public (regardless of futureland use) from exposure to as much as 52 ppm nitrate in the groundwater under the Horn RapidsLandfill have been discussed in the Pathway section of this document. Briefly, the groundwatermoving under the landfill is not being tapped for potable water now, since the 1100-Area is beingsupplied by the city of Richland. The area will continue to be so supplied after transfer of theland from federal control (5). When the nitrate-contaminated groundwater plume extends to theColumbia River, nitrate will quickly be diluted to undetectable levels by the 120,000 cubic feetper second flow of water (17).
Tetramethyloxirane (TMO) -- ATSDR has no comparison value for TMO. TMO wastentatively identified in 4 samples in borehole DP8 some 10 to 22 feet below the surface at theantifreeze and degreaser pit (1100-3) (3). Unless it was injected at that depth, it has beenmigrating downward toward the groundwater at an unknown rate. How this could affect thepublic health, and when, is uncertain in the absence of confirmation of its identity, additionalsampling to quantify rate of movement, and possible research (in the event of confirmedidentification) on its toxicity. For a discussion of possible toxicological implications of exposureto TMO, see Appendix D.
Implications of Exposure of People in Richland and Rural Benton County
At present, the public is not exposed to 1100-Area contaminants via the Groundwater southeastpathway (see Table 4). Municipal and private wells are either too far south to be in the path ofmigration of contaminated groundwater or the well water is sufficiently diluted with ColumbiaRiver water to prevent a health threat. The protective effect of mixing, shown by wellfieldnitrate concentrations closer to those of the Columbia River than to the groundwater taken fromDuke wells, may result from water from the Columbia River being pumped into the NorthRichland Wellfield faster than it is drawn from the wellfield for municipal use.
Implications of Exposure of People in the Tri-Cities Area
No one in this area has been or is being exposed to nitrates, trichloroethylene, or chromium from1100-Area groundwater contaminants in the plume moving northeast from the Horn RapidsLandfill because this plume has not yet reached the Columbia River. As discussed above, thehighly volatile trichloroethylene is unlikely to persist in surface water until it reaches a watersupply intake. Nitrate in the plume is in high enough concentration to be of concern if the wateris ingested by infants. However, there are no drinking water wells that tap the plume, and anyfuture residents would drink city water. In the future, the plume could eventually deposit thecontaminants in the river, where they would be diluted, most likely below the level of detection,before they reach water intakes for the cities.
Health data were not reviewed because the surrounding public was not found to be exposed tocontaminants originating in the 1100-Area, and people living nearby did not express concernabout being made ill by the nonradioactive contaminants specific to the 1100-Area. Healtheffects that could result from exposures to contaminants specific to other Hanford NPL sites willbe addressed as part of the public health assessments of those sites.
Discussions with local government and health officials and representatives of citizen groups andAmerican Indian tribes during 1992-1994 indicated that health concerns are generallyreservation-wide. This is true because the public and local governments view Hanford as anaggregate of all reservation facilities rather than as four NPL sites of which the 1100-Area is onesite. As with other DOE facilities, public concern tends to focus on radiological hazards. Theabsence of radiological contamination in the 1100-Area may explain the lack of public focus onthis NPL site. ATSDR representatives were unable to identify any community health concernsspecifically associated with the contaminants of the 1100-Area. Community health concernsspecifically associated with the contaminants of the other Hanford NPL sites will be addressed aspart of the public health assessments of those sites.